Most bus communication protocol adopts a communication process that transmits destination address information of transmit/receive (TX/RX) data in the first bus cycle and transmits/receives the TX/RX data in the next bus cycle. This communication process is performed in a register pipeline manner.
FIG. 1 is a diagram illustrating a process for transmitting data of a microprocessor bus.
Generally, an address bus transmits successive address data. Thus, there are many correlations between address data of the respective cycles. Generally, the address data increase or decrease successively, as illustrated in FIG. 1. In FIG. 1, ‘A’ denotes an overlap between the respective address data.
In this manner, signals of an address bus are small in the signal transition frequency (i.e., the number of signal transitions). However, if the address bus signals are serialized prior to transmission, their correlation is broken. If the address bus signals are serialized with their correlation broken, their signal transition increases greatly.
This is also true in the case of a data bus. Referring to FIG. 1, data bus signals, including data signals Data, Data1, Data2 and Data3 corresponding respectively to address signals A, A+1, A+2 and A+3, generally have a correlation therebetween like the address bus signals.
For example, in the case of multimedia data including image, audio, or video requiring a large amount of data transmission, the adjacent data signals generally have little or no difference therebetween.
However, like the address bus signals, if the multimedia data signals are serialized prior to transmission, their correlation is broken and their signal transition increases accordingly.
A signal transmission path or a conductive line external to the microprocessor has thousands to tens of thousands times the Capacitance (C) of a conductive line in a semiconductor device. Therefore, the former may consume thousands to tens of thousands times more power per signal transition than the latter.
What is therefore required is a method for preventing a sudden increase in signal transition frequency to suppress an increase in power consumption, when serializing the bus signals prior to transmission.